Utilization of original phosphogypsum for the preparation of foam concrete

Original phosphogypsum (PG), which is a waste of phosphoric acid manufacturing by dehydrating process, was used as raw material for manufacture of foam concrete. It was prepared by adjusting the mix proportion of the untreated phosphogypsum and a small amount of cement, GGBFS and quick lime, meantime, mixing with foam. A series of manufacturing parameters were investigated to determine the performance of specimens in this work, such as accelerator, quick lime, PG, supplementary cementitious materials and foam content, water to solid ratio, curing regimes etc. The results show the most excellent content of PG was 45-55%, cement to GGBFS ratio was 1, quick lime 4%, sulphoaluminate cement 2%. In the case of mixed without water reducing admixture, the W/S (water to solid ratio) from 0.4 to 0.5 is excellent. Most of the PG are as filler, and there is a small amount of sulfate in the PG also played a role in stimulating calcium silicon materials and generating ettringite to enhance compressive strength. Carbonation resistance of PG-cement-GGBFS system is better than PG-cement-FA system. The thermal conductivity of different density grade met the requirement of a Chinese standard. The principal minerals in PG foam concrete are needlelike AFt, floccular C-S-H and unreactive plate gypsum.